Bone Plate with Screw Hole Arrangement

ABSTRACT

An orthopedic screw system includes a screw with a locking head that can both lockingly engage in a fixed angle threaded screw hole to secure a plate to a bone without compression, and non-lockingly engage at a compression screw hole to provide compression between the plate and the bone. The structure of the system is particularly well adapted to plates and screw of small dimensions, such as screws smaller than 3.5 mm and is capable of providing high compressive force, on the order of 120 lbs of axial load, without significant plastic deformation between the screw and plate. Further, the screw holes are structured for arrangement in tight clusters on the bone plate, thereby facilitating a compact design on the bone plate.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. Ser. No. 13/313,350, filedDec. 7, 2011, which is hereby incorporated by reference herein in itsentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to surgery. More particularly, theinvention relates to orthopedic systems, including plates and screwstherefor.

2. State of the Art

Bone plates can be used to repair traumatic bone fractures. The platesare positioned on the bone and screws are inserted through holes in theplate and into underlying bone to secure the plate relative to the boneto aid in healing.

Various options are provided for coupling the plate to the bone. Atspecific locations on the bone and relative to a fracture it may beappropriate to use compressive fixation in which a compressive screw isinserted into a screw hole in the plate and the underlying bone tosecure the plate to the bone with compression. Such compression screwholes are often provided to a plate in a combination of round and oblongscrew holes. An oblong screw hole allows the plate to be positioned in atrial location on the bone. A hole is then drilled through a locationwithin the oblong screw hole and a compressive screw is advanced throughthe hole into a preferably slight contact with the plate. The plate maythen be moved relative to the screw into a final position before thecompressive screw is advanced to axially load the plate against thebone. In addition, round non-threaded screw holes in the plate areprovided to receive compressive screws at defined locations relative tothe plate and the underlying bone. Compression screw holes and screwscan be provided in varieties that permit both fixed angle andmulti-angular approaches for attachment of the plate to the underlyingbone.

At other locations relative to the fracture it may be appropriate to usea locking screw that is inserted into the plate and the underlying boneand then locked in relative to the plate with the locking screwretaining bone fragments in relation to the plate; such a screw does notapply significant compressive force between the plate and the bone.Locking screws often couple to the plate by a threaded engagementbetween external threads on the head of the screw and internal threadsformed in a screw hole.

Further, the requirements of a bone plate system that is of reduceddimension and thickness profile to accommodate smaller bonesnecessitates additional considerations. Providing a reduced profile boneplate system allows the plate and its associated screws to be used onbones of the extremities which are difficult to treat. This isespecially important for plates used to repair bone fractures where thebone has little protection by overlying soft tissues and is highlyvulnerable, for example, to accidental bumping as the fracture heals.Development of very thin, anatomically conforming bone plates hascreated new challenges related to plate-to-bone attachment. Morespecifically, improved designs for screw systems are needed to reducethe hardware that protrudes above the top surface of the plate andirritates and/or inflames the overlying tissues. Further, smaller screwsare weaker, particularly at the screw head around the driver socket, andprone to failure when torqued to apply axially loading.

Regardless of plate and screw size, there is a drive toward reducing theinventory of components necessary to complete a plating procedure.However, each of the compression screw holes and locking screw holesgenerally is structured to receive a different type of screw,particularly having different structure at the head of the screw. Thehead of the non-locking compression screw is structure for applicationof axial loads, whereas the head of the locking screw is structured tomechanically couple the screw directly to the plate. Moreover, each typeof screw is provided in several lengths within the surgical set. Thisrequires a level of inventory control that is difficult to maintain.Alternatively, with respect to prepackaged systems that are intended tocontain all necessary components for completing a plating procedure, thesheer number of components can lead to significant and expensive waste;this is untenable where health care costs are being managed.

Previously there has been some work to reduce the number of screwsrequired to be included in a bone plate system. By way of example,co-owned US Pub. No. 20100069969 discloses a system that convertslocking screws to compressive screws by attaching a washer element tothe head of the locking screws to increase the effective surface area ofthe screw head that applies the axial compressive load against theplate. While the number of required screws is decreased by such asystem, the system nevertheless requires the inclusion of washers andspecialized instrumentation to couple the washers to the screw heads.

SUMMARY OF THE INVENTION

An orthopedic screw system is provided that includes a plate with atleast one tapered and threaded locking screw hole and at least onenon-threaded compression screw hole which is in the form of a round holeor an oblong hole. The compression screw hole has an upper opening witha first diameter, a lower portion with a lowermost opening with asmaller second diameter, and a screw seat between the upper opening andlower portion.

The system also includes a single type of bone screw that can be used ineither type of screw hole to (i) mechanically lock relative to the platewhen the screw is inserted into the threaded locking hole or (ii)axially load the plate relative to the bone when the screw is insertedinto the compression screw hole. The screw has a head and a shaft. Thehead includes conically tapered external threads. A bearing annulussmaller than the head thread diameter is defined at the interface of thehead and the shaft. The shaft has bone engaging threads defining a minordiameter at the troughs and a major diameter at the crests. The majordiameter is larger than the second diameter of the compression screwhole, such that the shaft must be rotationally threaded through thelowermost opening of the compression screw hole to be longitudinallyadvanced therethrough. The bearing annulus is configured to present alarge surface area for the given diameter of the annulus and supports ahigh axial load on the screw seat of the compression holes. Further, thebearing annulus displaces the axially loads from weaker portions of thescrew head which could otherwise be subject to plastic deformation.

The system allows a single type of screw to be used in association witha plate to provide for axial compression loading in compression holesand locking fixation to the plate in locking holes. The system isparticularly well adapted to plates and screws of small dimensions, andis capable of applying high compression loads between the screws andplate at the compression holes without significant plastic deformation.

Furthermore, the system reduces the inventory of components required fora surgical plating procedure. Moreover, the system simplifies theprocedure, as the surgeon is able to use the same screw regardless ofthe type of screw fixation required.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a portion of a bone plate according tothe invention.

FIG. 2 is a view similar to FIG. 1 in which bone screws are received inscrew holes of the bone plate.

FIG. 3 is a top view of the portion of the bone plate.

FIG. 4 is a top view of a small portion of the bone plate showing athreaded screw hole according to the invention.

FIG. 5 is a section view of the bone plate along line 5-5 in FIG. 4.

FIG. 6 is a section view along line 6-6 in FIG. 3.

FIG. 7 is a top view of a small portion of the bone plate showing around compression screw hole according to the invention.

FIG. 8 is a section view of the bone plate across line 8-8 in FIG. 7.

FIG. 9 is a top view of a small portion of the bone plate showing anoblong compression screw hole according to the invention.

FIG. 10 is a section view of the bone plate across line 10-10 in FIG. 9.

FIG. 11 is a side elevation view of a bone screw according to theinvention.

FIG. 12 shows a partial section view of the bone screw of the inventionbeing partially inserted into the bone plate and bone.

FIG. 13 is a view similar to FIG. 12, showing full insertion of the bonescrew into the bone plate and bone.

FIG. 14 is a view similar to FIG. 13, showing full angled insertion ofthe bone screw into the bone plate and bone.

FIG. 15 is a cross-section view transverse to the longitudinal axis ofthe bone plate, showing an alternative embodiment of a compression screwhole according to the invention.

FIG. 16 is a partial section view showing the bone screw inserted intothe compression screw hole shown in FIG. 15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to FIG. 1, a bone plate 10 according to the invention isshown. The plate 10 shown has a straight portion 12 defining alongitudinal axis A_(P). The straight portion 12 of the plate may be aportion of a diaphyseal plate for placement along the diaphysis of along bone of an upper or lower extremity. Alternatively, the straightportion 12 may be one end of a metaphyseal plate for use at the end of along bone. As another alternative, the straight portion 12 may be asegment of any other plate having an elongate portion. Further, theplate 10 may be manufactured to assume other shapes that are suitablefor use on various bones throughout the human body. The plate 10 ismanufactured from metal, and more preferably machined from a solid blockof titanium or titanium alloy.

The plate 10 has an upper surface 14, a bone contacting lower surface 16and a thickness T defined between the upper and lower surfaces 14, 16. Aplurality of screw holes 18, 20, 22, described below, extend between theupper and lower surfaces 14, 16. In addition to the screw holes, theplate optionally includes a plurality of significantly smaller andpreferably cylindrical holes 23 that are sized to closely receiverespective K-wires for temporary fixation during an implantationprocedure. Referring to the screw holes, the plate is shown to includethree types of screw holes: a threaded round locking hole 18, anon-threaded round compression hole 20, and a non-threaded oblongcompression hole 22, each described further below. With respect to FIGS.2 and 3, a screw 24, described in more detail below, is shown insertedwithin each of the screw holes 18 and 20. As will also be described,such same screw 24 can also be inserted in screw hole 22. In accord withthe invention, the screw 24 regardless of the hole into which it isinserted has a common head and shaft design of common dimensions.

Referring to FIGS. 1, 4 and 5, the threaded screw hole 18 has threads 26helically arranged about its interior, and the hole is preferablysubstantially uniform about its internal circumference. The hole 18 istapered so as to have an upper opening 28 at or adjacent the uppersurface 14 of the plate with a diameter D_(U) larger than a diameterD_(L) at a lower opening 30 at or adjacent the lower surface 16 of theplate.

Turning now to FIGS. 1 and 7 and 8, according to a first embodiment ofthe invention, the round compression screw hole 20 has an upper opening32 at or adjacent the upper surface 14 of the plate 10 with a firstdiameter D₁ in each of two orthogonal directions and a lower opening 38is provided at or adjacent the lower surface 16 of the plate with asmaller second diameter D₂ in one direction and the first diameter D₁ ina direction orthogonal to the second diameter D₂. With reference back toFIG. 4, the first diameter D₁ is preferably larger than the diameterD_(U) of the upper opening of the threaded screw hole. The seconddiameter D₂ is preferably smaller than the diameter D_(L) of the loweropening of the threaded screw hole 18. The screw hole 20 has a centralaxis A_(C) extending through the centers of the upper and lower openings32, 38.

Turning back to FIGS. 7 and 8, two parallel rails 40 recessed relativeto the upper opening 38 extend across the screw hole. The upper surfaces42 of the rails 40 are angled relative to each other at approximately60°-90° and together define a screw seat 34. Vertically extending walls44 of the rails 40 define a lower portion 36 of the screw hole and havea thickness T_(R) extending in the same direction as the central axis ofthe compression screw hole 20. In the first embodiment, the rails 40extend parallel to the longitudinal axis A_(P) of the plate 10 (FIG. 1).

According to the first embodiment of the invention, the oblongcompression screw hole 22 is substantially similar to the roundcompression screw hole, but extended in diameter; i.e., length, alongthe dimension in which the rails extend; that is, the screw hole 22 doesnot have the same D₁ diameter at two relatively orthogonal directions.For clarity of the following description, reference numerals which referto elements similar to screw hole 20 are offset by 20 in screw hole 22.In accord therewith, screw hole 22 has an upper opening 52 with firstmajor diameter D_(M1) and a first minor diameter D_(m1), and a loweropening or slot 58 with a second major diameter D_(M2) and a secondminor diameter D_(m2). The first and second major diameters D_(M1) andD_(M2) are preferably of a common dimension, with the rails 60, and thusthe seat 54, extending on laterally opposite sides of the first andsecond major diameters D_(M1) and D_(M2), but not at the ends of thefirst and second major diameters. The second minor diameter D_(m2) issmaller than the first minor diameter D_(m1). Rails 60 extend lengthwisealong the screw hole 22, parallel to but on opposite sides of the secondmajor diameter D_(m2), and in the first embodiment parallel to thelongitudinal axis A_(P) of the plate. As with the round compressionscrew hole 20, upper surfaces 62 of the rails 60 define a screw seat 64,and vertically extending walls 64 of the rails 60 define a lower portion56 of the screw hole having the same thickness T_(R). The first andsecond minor diameters D_(m1) and D_(m2) of the oblong screw hole 22preferably correspond exactly in dimension to the first and seconddiameters D₁ and D₂ of the round compression screw hole 20.

Referring to FIGS. 1-3, the locking and compression holes 18, 20, 22 maybe situated along the longitudinal axis A_(P), offset from thelongitudinal axis, or provided in a combination of both on-axis andoff-axis locations. In the embodiment shown in FIG. 1, the compressionscrew holes 20, 22 are situated in alignment with the longitudinal axisA_(P), whereas the threaded locking holes 18 are situated offset fromthe longitudinal axis. Further, referring to FIG. 5, the threadedlocking holes 18 are oriented along an axis A_(H) at a transverse andpreferably acute angle, e.g., 20°±10°, relative to a line normal L tothe lower surface 16 of the bone plate 10.

As shown in FIGS. 2 and 3, according to a preferred aspect of theinvention, the system also includes the single type of bone screw 24that can be used in either the threaded screw hole 18 or non-threadedcompression screw holes 20, 22 to (i) mechanically lock relative to theplate when the screw is inserted into the threaded locking hole, or (ii)axially load the plate 10 relative to bone when the screw is insertedinto the compression screw holes. The screw 24, as described below,operates as a standard locking screw when inserted into the threadedscrew hole 18. However, when inserted into the round or oblongcompression screw holes 20, 22, the screw 24 has structure that mateswith the screw seats 34, 54 (FIGS. 8 and 10) thereof to allow the screwto apply significant axial load to the plate without plastic deformationof the screw. This is significant, as plastic deformation could resultin metal debris which could lead to tissue irritation at the implantsite. Further, significant plastic deformation could result in weldingof the screw to the plate, rendering removal of the screw and/orplate—if necessary—a difficult and potentially dangerous procedure.

Turning to FIG. 11, the screw 24 has a head 82 and a shaft 84. The head82 includes conically tapered external threads 86 terminating in anupper peripheral rim 88 at the trailing end of the threads thatfunctions as a stop. The threads 86 preferably taper at 4°-10° per side,more preferably at 6° per side. The head 82 also includes a driverengagement socket 90 for receiving a torque driver tool with acorresponding shape. By way of example, the socket 90 may define asquare or hexagonal cross-section (FIG. 6). According to a preferredaspect of the invention, at the transition of the head 82 to the shaft84, a bearing annulus 92 is provided. The bearing annulus 92 is smallerthan the threaded portion of the head and forms a preferably smooth 90°conical portion. The angle of the lower surface of the bearing annulus92 presents a large surface area for the given diameter of the annulusand is advantageous in supporting high axial loads on the screw seats34, 54 of the compression holes. Further, the bearing annulus 92displaces the axially loads from the weaker portions of the screw head,particularly at the thinnest portion of the wall of the screw headbetween the driver socket 90 and the external threads 86, which couldotherwise cause the screw to plastically deform and potentially fail.

The shaft 84 has bone engaging threads 94 which define a shaft majordiameter D_(SM), a shaft minor diameter D_(Sm), a shaft thread pitchS_(P). The shaft thread pitch S_(P) is approximate to, but greater than,the thickness T_(R) of the vertical walls 44, 64 of the compressionscrew holes 20, 22. The shaft major diameter D_(SM) is larger than thesecond diameter D₂ (FIG. 7) of the round compression screw hole 20 (aswell as the corresponding second minor diameter D_(m2) of the oblongcompression screw hole 22, FIG. 9). More particularly, the dimensions ofthe shaft 84 of the screw equate to the second diameter D₂ of the roundcompression screw hole, as follows:

D ₂(D _(SM) +D _(SM))/2+up to 4% for clearance.

Turning to FIG. 12, in view of the relationship of the dimensions of thecomponents, the shaft 84 of the screw must be rotationally threadthrough the lowermost opening 38 of the compression screw hole 20 to belongitudinally advanced therethrough. This is transparent to the user,as the screw shaft 84 is being simultaneously threaded through bone 100.Referring to FIG. 13, when the screw 24 is advanced such that thebearing annulus 92 of the head contacts the screw seat 34, furthertorqueing of the screw causes the load to be carried on the screw at thebearing annulus. As shown in FIG. 14, the compression screw hole canalso accommodate approximately 2°-3° of lateral angulation of the shaft84 on each side of line normal L to the lower surface 16 of the plate(for a total of 4°-6° of angular variability). The screw is insertedwithin the oblong screw hole in the same manner. However, the oblongscrew hole provides the option to adjust the longitudinal displacementof the plate relative to the screw before the screw is fully loadedagainst the plate.

The holes 18, 20, 22 and screw 24 are structured for clustering togetheron the bone plate. The screw head, with the bearing annulus 92 locateddistally of the head threads 86, is of a particularly compact design.This permits more screw holes 18, 20, 22 sized to accommodate the screwto be formed in the plate 10 to provide the surgeon with greaterflexibility of screw placement into a bone. In addition, referring toFIG. 3, the screw holes 18, 20, 22 can be spaced closer together in acluster 96 to provide the advantages of placement on both plates oflarge and relatively small dimensions. In such a cluster 96, a threadedhole 18 is located substantially equidistantly between two compressionscrew holes, and more preferably between a round compression screw hole20 and an oblong compression screw hole 22. Such a cluster 96 preferablyprovides screw hole spacing in a dense pattern, wherein portions of eachof a threaded hole 18 and the both types of the compression holes 20, 22are located within a bounding area bounded by a circle preferably nolarger than twice the diameter D_(U) of the upper opening 28 of thethreaded hole 18 (as shown at bounding area BA₁) or more preferably 1.5diameters of the diameter D_(U) of the upper opening 28 of the threadedhole 18 (as shown at bounding area BA₂) in FIG. 3. Further, each of theclusters as well as the indicated bounding areas preferably alsoincludes a portion of at least one of the guidewire holes 23. Multipleclusters 96 of screw holes are preferably provided to the bone plate.

In one method of use, referring to FIGS. 9-11, the plate is positionedon the bone at a location suited for stabilization of the fracture. Ahole is drilled through an oblong compression hole 22 in the plate andinto the underlying bone, and a screw 24 is inserted into the hole. Asindicated above, as (i) the major diameter D_(SM) of the screw shaft islarger than the second minor diameter D_(m2) (or transverse dimension ofthe slot) of the compression screw hole 22, (ii) the minor diameterD_(Sm) of the screw shaft is smaller than the second minor diameterD_(m2), and (iii) the vertical wall thickness T_(R) of the rails 60defining the lowermost portion of the compression slot is smaller thanthe pitch S_(P) of the shaft thread, the screw shaft can and must berotatably threaded through the wall portion 64 to advance the shaft 84through the compression hole. Once the screw is advanced into the bonesuch that the screw head 82 is proximate the screw seat 54 (but notfully loaded against the plate) the plate 10 may be translated relativeto the screw 24. With the screw shaft threads 94 engaging the bone, thescrew 24 is then driven to load the bearing annulus 92 against the screwseat 54 and thereby force the plate 10 and the bone against each other.With as little as 5-6 in-lbs torque, 120 lbs of axial load can begenerated between the bearing annulus 92 and the seat 54 with no load onor damage to the screw head threads 86.

Before or after tightening the screw through the oblong compressionhole, additional holes are drilled into the bone through the roundcompression holes and/or the locking holes (FIG. 1-3). For all holesdrilled through the round compression holes and into the underlyingbone, respective screws are inserted through such holes and drivenagainst the plate to load the plate against the bone, as described withrespect to the oblong compression holes, without the option to translatethe plate prior to final loading. As shown in FIG. 14, such screws maybe inserted into the compression screw holes (round and oblong) withangular variability of up to 2°-3° per side, within a plane transverseto the longitudinal axis of the slot of the screw hole and across bothrails of the screw hole. Even at such angles, the bearing annulus 92support the loads placed thereon without plastic deformation of thehead. Turning to FIG. 6, for all holes drilled through the threadedholes 18 and into the underlying bone, the shaft 84 is advanced throughthe threaded screw hole into an underlying drilled hole and the screwhead 82 is threaded into locking engagement with the internal threads 26of the screw hole. The shaft threads 94 retain bone and bone fragments100 beneath the plate 10 and hold such bone and fragments in a stableand preferably fixed position relative to the plate.

Turning back to FIG. 9, in another method of use, the design of thescrew seat 54 of the oblong compression holes 22, with no seat portionlocated in alignment with the first and second major diameters D_(M1),D_(M2), permits the oblong compression hole to be used in application ofdynamic compression across a fracture. In dynamic compression, the plateis initially secured to the bone with one or more screws 24 only at oneside of a fracture. Then, on the other side of the fracture, a screw 24is inserted at the end of an oblong screw hole located further from thefracture. Because the oblong compression screw hole has no seat alongits first and second major diameters D_(M1), D_(M2), the shaft 84 of thescrew can be closely approximated to the indicated ‘further’ end withoutinterference with a screw seat. The screw shaft 84 is advanced into thebone at such location until the bearing annulus 92 of the head 82 of thescrew 24 abuts the upper edge, e.g., at edge 98, of the screw hole.Then, further advancement causes the screw 24 to be longitudinallytranslated within the slot 66 of screw hole toward the screw seat 54 sothat the bearing annulus 92 can be seated deeper. As the screw isattached to the bone, this causes the bone portion to which the screw isattached to be displaced in a manner that reduces the fracture.Additional screws can be inserted as necessary to maintain the reductionand complete the fixation.

Referring now to FIGS. 15 and 16, a bone plate system may include asecond embodiment of compression screw holes 120 for use in associationwith the screw 24. The round compression screw hole 120 includes aconically shaped hole 121 with an upper opening 132 with a firstdiameter and a lower opening 138 with a second diameter. The screw holeis deeper to accommodate the rim 88 of the screw head 82. In distinctionfrom the first embodiment, the round compression hole has a single rail140 extending from one side thereof below the upper opening 132 todefine screw seat 134 and a lower portion 136. The lower opening definesa slot 146 adjacent the rail 140. The second embodiment of the oblongscrew hole 122 is of similar design, with one upper diameter larger thanan orthogonal upper diameter. The second embodiment of the compressionscrew holes 120 (, 122) provides for a screw seat 134 for supporting thebearing annulus 92 of the screw 24 only at one side of the screw hole122. Constraining the angle of the screw by the provision of a conicalhole ensures that the bearing annulus applies the load to the screwseat. Further, while only a single rail 140 is provided, the seconddiameter of the lower opening 138 (or second minor diameter of an oblongcompression screw hole) continues to be smaller than the screw shaftmajor diameter and larger than the screw shaft minor diameter D_(SM)(for reference see FIG. 11). Further, the lower portion 136 defined bythe rail 140 has a thickness T_(R) along vertical wall 144 that issmaller than the pitch S_(P) of the screw shaft threads. As such, thescrew shaft 94 can and must be inserted through the lower opening 138 ofthe compression hole by rotational advancement.

In all embodiments, the system allows a single type of screw to be usedin association with a plate to provide for axial loading of the plate tothe bone at compression holes and locking fixation of the screws to theplate at locking holes. Thus, the system reduces the inventory ofcomponents required for a surgical plating procedure. Moreover, thesystem simplifies the procedure, as the surgeon is able to use the samescrew regardless of the type of screw fixation required.

The system is particularly well adapted to plates and screws of smalldimensions, such as screws at or smaller than 3.5 mm, or moreparticularly at or smaller than 2.7 mm, and is capable of providing highaxial loads, on the order of 120 lbs of axial load, without significantplastic deformation between the screw and plate.

There have been described and illustrated herein embodiments of a boneplating and screw system. While particular embodiments of the inventionhave been described, it is not intended that the invention be limitedthereto, as it is intended that the invention be as broad in scope asthe art will allow and that the specification be read likewise. It willtherefore be appreciated by those skilled in the art that yet othermodifications could be made to the provided invention without deviatingfrom its spirit and scope as claimed.

What is claimed is:
 1. A bone plate for use in stabilizing a fracture ofa bone, comprising: a bone supporting metal plate having an uppersurface, a bone contacting lower surface, and a plurality of a screwholes extending between said upper and lower surfaces, said plurality ofscrew holes including, i) a tapered locking screw hole having threadshelically arranged about its interior, said locking screw hole having anupper opening with an upper diameter, and a lower opening with a lowerdiameter, and ii) first and second compression screw holes having anupper opening with a first diameter, and a lower opening with a seconddiameter smaller than said first diameter in one direction and a thirddiameter equal to said first diameter in a direction orthogonal to thesecond diameter, and defining a central axis through the centers of theupper and lower openings, at least one rail extending across a portionof said compression screw hole to define a screw seat with an angledupper surface, and a vertical wall with a thickness extending in thesame dimension as a central axis of the compression screw hole, whereinportions of each of said upper opening of said locking screw hole andsaid upper openings of said first and second compression screw holes arelocated within a bounding area bounded by a bounding circle no largerthan twice said diameter of said upper opening of said locking screwhole such that said locking screw hole and said first and secondcompression screw holes are arranged in a cluster.
 2. A bone plateaccording to claim 1, wherein: said bounding circle is no larger than1.5 times said diameter of said upper opening of said locking screwhole.
 3. A bone plate according to claim 1, wherein: said locking screwhole is located substantially equidistantly between said first andsecond compression screw holes.
 4. A bone plate according to claim 1,wherein: at least a portion of a non-threaded cylindrical hole smallerthan each of said screw holes and sized for closely receiving a K-wireis provided within said bounding circle.
 5. A bone plate according toclaim 4, wherein: said bounding circle is no larger than 1.5 times saiddiameter of said upper opening of said locking screw hole.
 6. A boneplate according to claim 1, wherein: said bone plate includes aplurality of said clusters of screw holes.
 7. A bone plate according toclaim 1, wherein: said first and second compression screw holes includesa round compression screw hole and an oblong compression screw hole. 8.A bone plate according to claim 7, wherein: said plate defines alongitudinal axis, said at least one of said first and secondcompression screw holes is situated along said longitudinal axis, andsaid locking screw hole is situated offset from said longitudinal axis.9. A bone plate according to claim 8, wherein: said locking screw holeextends along an axis oriented at an acute angle relative to a linenormal to said lower surface of said bone plate.
 10. A bone plateaccording to claim 8, wherein: both of said first and second compressionscrew holes are situated along said longitudinal axis.
 11. A bone platekit for use in stabilizing a fracture of a bone, comprising: a) a bonesupporting metal plate having an upper surface, a bone contacting lowersurface, and a plurality of a screw holes extending between said upperand lower surfaces, said plurality of screw holes including, i) atapered locking screw hole having threads helically arranged about itsinterior, said locking screw hole having an upper opening with an upperdiameter, and a lower opening with a lower diameter, and ii) first andsecond compression screw holes having an upper opening with a firstdiameter, and a lower opening with a second diameter smaller than saidfirst diameter in one direction and a third diameter equal to said firstdiameter in a direction orthogonal to the second diameter, and defininga central axis through the centers of the upper and lower openings, atleast one rail extending across a portion of said compression screw holeto define a screw seat with an angled upper surface, and a vertical wallwith a thickness extending in the same dimension as a central axis ofthe compression screw hole, and wherein portions of each of said upperopening of said locking screw hole and said upper openings of said firstand second compression screw holes are located within a bounding areabounded by a bounding circle no larger than twice said upper diameter ofsaid upper opening of said locking screw hole such that said lockingscrew hole and said first and second compression screw holes arearranged in a cluster; and b) a plurality of like bone screws, eachhaving a head and a shaft, for respective insertion into said lockingscrew hole and said first and second compression screw holes.
 12. A boneplate kit according to claim 11, wherein: said head of each of said bonescrews includes conically tapered external threads, a proximalperipheral rim, a driver engagement socket at a proximal end of saidscrew head for receiving a torque driver tool, and a lower bearingannulus distal of said external threads, said bearing annulus smaller indiameter than said external threads and defined by a conical surface,and said shaft of each of said bone screws includes bone engagingthreads defining a shaft major diameter, a shaft minor diameter, and ashaft thread pitch, wherein, said shaft thread pitch is approximate to,but greater than, said thickness of said vertical wall of said first andsecond compression screw holes, said shaft major diameter is larger thansaid second diameter of said first and second compression screw hole,and said shaft minor diameter is smaller than said second diameter ofsaid first and second compression screw holes, wherein, a first of saidbone screws can be inserted into said tapered locking screw hole, withsaid shaft extending through said lower opening of said locking screwhole and said tapered threads of said head of said bone screw engagingsaid internal threads of said locking screw hole to engage said screwrelative to said plate, and a second and third of said bone screws canbe respectively rotatably inserted into said first and secondcompression screw holes in a direction from said upper surface of saidplate to said lower surface of said plate to cause said screw shaft ofsaid bone screw to threadedly engage with said plate at said loweropening of the respective of said first and second compression screwholes and into the bone, and as said screw shaft is advanced into thebone, said bearing annulus axially loads against said screw seat of saidrespective first and second compression screw holes.
 13. A bone plateaccording to claim 12, wherein: said plate defines a longitudinal axis,said at least one of said first and second compression screw holes issituated along said longitudinal axis, and said locking screw hole issituated offset from said longitudinal axis.
 14. A bone plate accordingto claim 13, wherein: said locking screw hole extends along an axisoriented at an acute angle relative to a line normal to said lowersurface of said bone plate.
 15. A bone plate according to claim 13,wherein: both of said first and second compression screw holes aresituated along said longitudinal axis.
 16. A bone plate kit for use instabilizing a fracture of a bone, comprising: a) a bone plate having anupper surface, a bone contacting lower surface, and a plurality of ascrew holes extending between the upper and lower surfaces, saidplurality of screw holes including, i) a tapered threaded screw holehaving threads helically arranged about its interior, said threadedscrew hole having an upper opening with a upper diameter, and a loweropening with a lower diameter, and ii) a round compression screw holehaving an upper opening with a first diameter, and a lower opening witha second diameter smaller than said first diameter in one direction anda third diameter equal to said first diameter in a direction orthogonalto the second diameter, and defining a central axis through the centersof said upper and lower openings, at least one rail extending across aportion of said round compression screw hole to define a screw seat withan angled upper surface, and a vertical wall with a thickness extendingin the same dimension as a central axis of said round compression screwhole, and iii) an oblong compression screw hole having an upper openingwith a first major diameter and a first minor diameter, and a loweropening with a second major diameter equal to the first major diameterand a second minor diameter smaller than said first minor diameter, anddefining a central axis through the centers of the upper and loweropenings, at least one rail extending across a portion of said oblongscrew hole to define a screw seat with an angled upper surface, and avertical wall with a thickness extending in the same direction as acentral axis of said oblong screw hole, wherein portions of each of saidupper openings of said locking screw, said round compression screw hole,and said oblong compression screw hole are located within a boundingarea bounded by a bounding circle no larger than twice said diameter ofsaid upper opening of said locking screw hole such that said lockingscrew hole, said round compression screw hole, and said oblongcompression screw are arranged in a cluster.
 17. A bone plate accordingto claim 16, wherein: said bounding circle is no larger than 1.5 timessaid diameter of said upper opening of said locking screw hole.
 18. Abone plate according to claim 16, wherein: said locking screw hole islocated substantially equidistantly between said first and secondcompression screw holes.
 19. A bone plate according to claim 16,wherein: at least a portion of a non-threaded cylindrical hole smallerthan each of said screw holes and sized for closely receiving a K-wireis provided within said bounding circle.
 20. A bone plate according toclaim 19, wherein: said bounding circle is no larger than 1.5 times saiddiameter of said upper opening of said locking screw hole.
 21. A boneplate according to claim 19, wherein: said bone plate includes aplurality of said clusters of screw holes.
 22. A bone plate according toclaim 16, wherein: said plate defines a longitudinal axis, said at leastone of said round compression screw hole and said oblong compressionscrew hole is situated along said longitudinal axis, and said taperedthreaded screw hole is situated offset from said longitudinal axis. 23.A bone plate according to claim 22, wherein: said tapered threaded screwhole extends along an axis oriented at an acute angle relative to a linenormal to said lower surface of said bone plate.
 24. A bone plateaccording to claim 22, wherein: both of said round compression screwholes and said oblong compression screw hole are situated along saidlongitudinal axis.
 25. A bone plate according to claim 16, incombination with a plurality of like bone screws, each having a head anda shaft, for respective insertion into said tapered threaded, roundcompression, and oblong compression screw holes.
 26. A bone plate foruse in stabilizing a fracture of a bone, comprising: a bone supportingmetal plate having an upper surface, a bone contacting lower surface,and defining a longitudinal axis, and a plurality of a screw holesextending between said upper and lower surfaces, said plurality of screwholes including, i) a tapered locking screw hole having threadshelically arranged about its interior, said locking screw hole having anupper opening with an upper diameter, and a lower opening with a lowerdiameter, said tapered locking screw located offset from saidlongitudinal axis and extending along an axis oriented at an acute anglerelative to a line normal to said lower surface of said bone plate, andii) a round compression screw hole having an upper opening with a firstdiameter, and a lower opening with a second diameter smaller than saidfirst diameter in one direction and a third diameter equal to said firstdiameter in a direction orthogonal to the second diameter, and defininga central axis through the centers of said upper and lower openings, andiii) an oblong compression screw hole having an upper opening with afirst major diameter and a first minor diameter, and a lower openingwith a second major diameter equal to the first major diameter and asecond minor diameter smaller than said first minor diameter, anddefining a central axis through the centers of the upper and loweropenings, at least one of said oblong round compression screw hole andsaid oblong compression screw hole situated along said longitudinalaxis, wherein portions of each of said upper openings of said lockingscrew, said round compression screw hole, and said oblong compressionscrew hole are located within a bounding area bounded by a boundingcircle no larger than twice said diameter of said upper opening of saidlocking screw hole such that said locking screw hole, said roundcompression screw hole, and said oblong compression screw are arrangedin a cluster.
 27. A bone plate according to claim 26, wherein: saidbounding circle is no larger than 1.5 times said diameter of said upperopening of said locking screw hole.
 28. A bone plate according to claim26, wherein: said tapered locking screw hole is located substantiallyequidistantly between said round and oblong compression screw holes. 29.A bone plate according to claim 26, wherein: at least a portion of anon-threaded cylindrical hole smaller than each of said screw holes andsized for closely receiving a K-wire is provided within said boundingcircle.
 30. A bone plate according to claim 26, wherein: each of saidround compression screw hole and said oblong compression screw hole aresituated along said longitudinal axis.